Pentachlorophenol Sorption by Rhizopus oryzae ENHE: pH and Temperature Effects

In this work, the sorption of pentachlorophenol (PCP) by non-viable biomass of Rhizopus oryzae ENHE was evaluated. The kinetics and isotherm studies were performed at pH 5.0, 6.0, and 8.0. The point of zero charge of the biomass was determined; this value allowed us to explain the changes of pH during sorption studies. The analyzed experimental kinetic data revealed that Ho's model adjusted better to the experimental data than Lagergren's model. PCP sorption was fast; an equilibrium sorption time was reached within 30 min, regardless of pH. PCP sorption at pH 5.0 and 6.0 was better described by the Freundlich isotherm than by the Langmuir isotherm. In contrast, at pH 8.0, the Langmuir isotherm describes better the PCP sorption. Sorption data showed that at pH 5.0 and 6.0, the sorption capacity of PCP was higher than at pH 8.0. Sorption of PCP by the fungal biomass occurred spontaneously; it was endothermic and due to physical sorption. Finally, FT-IR analysis of the dried biomass indicated that amino and hydroxyl groups were involved in the sorption of PCP. This work is one of the few reporting the effect of pH and temperature on the sorption of PCP by microbial biomass from a filamentous fungus belonging to the genus Rhizopus.